This invention relates to coupling devices for attaching an implement, such as a large bucket, to a power operated boom of a machine, such as a backhoe or excavator.
It is known to provide excavators, power shovels and backhoes with different sizes and types of material handling implements, such as buckets, to permit various operations. For example, a large bucket may be required for a backhoe to carry out certain types of digging, while a smaller bucket may be more appropriate for another digging job. Changing from one bucket or implement to another can be a problem because of the time and labor expended in the changeover and the difficulties that can be encountered. A backhoe bucket or a shovel implement can be very heavy and awkward to manipulate to the required position. Devices that permit the quick and relatively easy detachment of an existing bucket from the power operated boom and that permit a new bucket to be attached relatively easily and quickly are now desired by the earth handling industry, including contractors and operators of earth handling equipment.
A number of mechanisms have been developed previously in an effort to provide a mechanism that can quickly connect to an excavator bucket and then disconnect later, when required.
U.S. Pat. No. 5,310,275 issued May 10, 1994 to E. L. Lovitt discloses a quick coupler for heavy equipment implements. A pair of hydraulic pistons are used to secure a shovel to a boom arm of a heavy vehicle. The shovel and the boom arm have a set of xe2x80x9cVxe2x80x9d shaped guides which come into contact to allow the shovel to be pivoted into position. The shovel also has two horizontally extending members which fit into two slots in the arm and allow the pistons with their movable shafts to engage them in order to secure the shovel.
U.S. Pat. No. 4,586,867 issued May 6, 1986 to R. Stafford also discloses a quick coupler which utilizes a pair of hydraulic cylinders attached to movable bolts to engage a bucket to a boom arm of a heavy vehicle. This specification also teaches the use of a cylindrical bar mated with a curved channel member for support, while the bucket is secured to the boom arm by the locking bolts connected to the hydraulic cylinders, these bolts extending through holes in plates attached to the bucket.
U.S. Pat. No. 5,915,837 issued Jun. 29, 1999 to Caterpillar Inc. teaches a quick coupling apparatus that incorporates the use of a piston controlled securing bar and curved hook shaped member for engaging and rotating about a cylindrical member attached to a boom arm of a heavy machine. This patent also discloses the use of a mated pair of curved members for the transport of force. This apparatus using linkage members that are positioned in a locked position when the power device is attached to the bucket. The linkage members include a latch having a pair of spaced apart ends.
U.S. Pat. No. 5,024,010 issued Jun. 18, 1991 to Fritiof Hulden discloses a quick coupling system that uses hooks to rotatably connect a bucket to a boom arm. A piston is used to engage a securing apparatus to the bucket. This coupling employs a pair of parallel link arms that are pivotably mounted on the boom arm. There is a locking unit held between these arms that has a slidable tension pin that engages a wedge support affixed to the bucket.
It is an object of the present invention to provide a quick coupling apparatus for attaching an implement such as a bucket to a boom wherein the apparatus can be manufactured at a reasonable cost and is relatively easy for a machine operator to use.
It is a further object of the present invention to provide a coupling apparatus that employs wedge shaped connecting members and a hydraulically operated locking device to secure the coupling apparatus in place, therefore providing a rigid, secure connection between the material handling implement, such as a bucket, and a power operated boom to which the bucket is attached.
According to one aspect of the invention, a coupling device for releasably connecting a boom arm to a tool, such as a material handling bucket, comprises a coupling frame adapted for connection to the boom and having wedge members provided on opposite, vertically extending sides thereof and projecting outwardly and in a transverse direction from the vertically extending sides. These wedge members are adapted to engage in wedge shaped channels formed by connecting members mounted on the tool. There is also a fluid actuated mechanism for securing the wedge members in the wedge-shaped channels. This locking mechanism is mounted on the coupling frame and includes a fluid actuator, at least one locking bar movable by the fluid actuator between a locking position and an unlocked position, and a track rigidly connected to the coupling frame. The track is for guiding movement of the at least one locking bar. In particular, the at least one locking bar is slidable along the track between the locking position and the unlocked position. During use of this coupling device, in the locking position, the at least one locking bar extends into a cooperating opening provided on the tool and thereby prevents the coupling device from detaching from the tool.
The preferred coupling frame comprises two, parallel connecting plates forming opposite sides of the coupling frame and rigid connecting frame members extending between and joining the connecting plates. The connecting plates both have pin-receiving apertures for pivotably connecting the coupling device to the boom arm by means of one or more connecting pins.
The preferred fluid actuator includes a double acting hydraulic cylinder having two piston rods extending from two opposite ends of the cylinder.
According to another aspect of the invention, a combination of a tool attachment and a coupling device for releasably coupling the tool attachment to a boom arm is provided. The tool attachment includes two spaced-apart connecting members arranged on a side of the tool attachment and each of these connecting members forms a wedge-shaped channel which is open at one end thereof. The coupling device comprises a coupling frame adapted for connection to the boom and having wedging devices provided on opposite sides thereof. Each wedging device is adapted to slide into a respective one of the wedge-shaped channels by means of the open end of the channel and to engage a respective one of the connecting members. A locking mechanism for securing the wedging devices in the wedge-shaped channels includes a fluid actuator and at least one locking bar movable by the fluid actuator between a locking position and an unlocked position. When the coupling device is attached to the tool attachment, the at least one locking bar extends into a bar receiving opening formed on the side of the tool attachment and thereby prevents the coupling device from detaching from the tool attachment.
In the preferred combination, the connecting members are parallel metal rail members and each wedge-shaped channel is formed on an inner side of its respective rail member so that the two wedge-shaped channels face one another.
According to still another aspect of this invention, a coupling device for releasably connecting a movable arm to a tool includes a coupling frame pivotably attachable to the movable arm, this frame including a pair of spaced-apart mounting plates each having a pair of pin-receiving holes with the holes of one mounting plate being aligned with the corresponding holes of the other mounting plate. Two wedge members are rigidly mounted on outer surfaces of the mounting plates with each of the wedge members mounted on a respective one of the mounting plates and projecting from a side thereof furthest from the other mounting plate. The wedge members are adapted for insertion in connecting channels provided on a side of the tool. A locking mechanism is provided as well to secure the wedge members in the channels, this mechanism including a fluid operated actuator attached to the coupling frame and at least one locking member slidable along a guide provided on the coupling frame between a locking position and an unlocked position. During use of this coupling device, the at least one locking member can be extended into a cooperating opening provided on the tool by the fluid operated actuator in order to prevent the coupling device from separating from the tool.
Further features and advantages will become apparent from the following detailed description of a preferred embodiment taken in conjunction with the accompanying drawings.